(1) Field of the Invention
The present invention relates to a broadcast recording apparatus which accumulates and reproduces a broadcast wave. In particular, the present invention relates to a mechanism which accumulates data of an application program included in a broadcast wave sent repeatedly as well as video/audio data sent synchronized with this data, and which reproduces this in synchronization with the video audio data.
(2) Description of the Related Art
Various data is included in a broadcast wave sent from a broadcasting station. In that data, there is data that is sent in time sequence, such as video/audio, and data that is sent repeatedly at a set interval. In terms of data that is sent repeatedly at a set interval, there exists, for example, data such as data broadcast represented by BML, and application programs (hereafter, referred to as applications) sent in a broadcast wave together with the video/audio, and so on. While it is not possible to re-acquire data sent in time sequence when acquisition fails once, with data sent repeatedly at a set interval, the same data is repeatedly sent, and therefore it is possible to re-acquire data even when acquisition has failed once.
Presently, the specifications regarding an environment, in which a broadcast wave that includes this type of video/audio and application is received and the application and video/audio are executed in synchronization, have been developed and are in operation. For example, a specification called Digital Video Broadcasting-Multimedia Home Platform (DVB-MHP) has been developed in Europe, and operations according to the specification are already commencing. In addition, a specification supporting a cable broadcast environment, called Open Cable Application Platform (OCAP), is being developed in the United States, and operations are planned to commence in 2005.
Furthermore, OCAP-DVR, which adds a function where a user of the OCAP specification can record and reproduce a selected service, is recently under development. Here, a service includes video/audio and an application related to the video/audio. Therefore, a function which accumulates video/audio as well as an application, and a function which executes the application in synchronization with the accumulated video/audio, are in demand.
Note that it is mentioned earlier that there is data in a broadcast wave that is repeatedly sent. However, in the aforementioned MHP/OCAP/OCAP-DVR specifications, a table which expresses the structure of a television program in the broadcast wave, a table which expresses control information of the application, and so on, in addition to carousel-form data of the application, exist as the data repeatedly sent in the broadcast wave.
In MHP/OCAP/OCAP-DVR, a method is provided in which same applications are started and terminated in accordance with control information denoted in Application Control Information (AIT); in OCAP-DVR, when a recorded broadcast wave is reproduced, the application is acquired and accumulated from the broadcast wave each time the application is started and terminated, which is a wasteful use of filter resources and a recording area.
The broadcast recording apparatus is, for example, a DVD or HDD installed as the recording area, but in general, these recording areas are limited. Additionally, in the abovementioned MHP/OCAP/OCAP-DVR specifications, when acquiring each kind of abovementioned table from a broadcast wave received from a broadcast station or a broadcast wave stored in the recording area, filter resources for extracting each table from the broadcast wave are required on a per-table basis. Also, during “trick play” (high-speed reproduction, skip reproduction, and so on) as prescribed in the OCAP-DVR specifications, it is difficult to extract the tables from the broadcast wave stored in the recording area in real-time. In particular, regarding acquisition during skip reproduction of a table which has position information of a skip destination (NPT coefficient), it is necessary to acquire a table in which that position information is multiplexed with a previous/next time which differs from the time of reproduction of the video/audio; however, depending on general filter resources, it is not possible to acquire such a table in which the time of reproduction of the video/audio is multiplexed with the different previous/next time. Because of this, it is preferable to accumulate each table extracted during accumulation in a form different from the broadcast wave, thus reducing the table extraction processing during reproduction. Therefore, when accumulating/reproducing data such as applications and various tables repeatedly sent in the broadcast wave, a device which accumulates/reproduces efficiently without wasteful consumption of resources, such as filter resources for extracting each kind of table from the recording area, broadcast wave, and so on, is necessary.
In Patent Reference 1 (Japanese Laid-Open Patent No. 2001-8176) (FIG. 1), when accumulating carousel-form data sent repeatedly, a version check is executed on the acquired data, and reduction of a recording area is realized by recording only data of a new version and not recording data of an identical version. In addition, the data of each version is recorded associated with a period of validity, and it is possible to realize a version change of the data during reproduction by creating a stream which synchronizes video/audio with the data during reproduction. Here, data of an identical version refers to when the present data sent repeatedly does not differ from the previous data, and data of a new version refers to when the present data sent repeatedly does differ from the previous data.
In Patent Reference 2 (Japanese Laid-Open Patent No. 2004-502350), reduction of a recording area is realized by recording repeatedly-sent carousel-form data in a module unit as prescribed in the Digital Storage Media—Command & Control (DSMCC), without recording the data as a stream. In addition, it is possible to realize a version change of the module during reproduction by recording each version of the module associated with a period of validity.
In the technologies of Patent References 1 and 2, it is possible to realize reduction of the recording area by recording each version of the data with a period of validity, and to realize a version change of the data during reproduction, without the repeatedly-sent carousel-form data overlapping.
The application data which is the carousel-form data prescribed in the abovementioned MHP/OCAP/OCAP-DVR specifications is formed in an object unit prescribed by DSMCC specifications. However, between Patent References 1 and 2, reduction of the recording area through recording without overlapping, in the module unit prescribed by the DSMCC specifications, is described, but data recording in object units as prescribed by the DSMCC specifications is not described. In actuality, because object unit data is a more detailed data which has eliminated unnecessary data from the module unit data, object unit data leaves more room for improvement in terms of improving wasteful consumption of recording areas by data recording in module units.
In addition, as mentioned earlier, in the MHP/OCAP/OCAP-DVR specifications, a table which expresses the structure of a television program in the broadcast wave, a table which expresses control information of the application, and so on, exist, in addition to carousel-form data of the application, as the data repeatedly sent in the broadcast wave. However, Patent Reference 1 and 2 are technologies regarding only efficient recording of carousel-form data. In the conventional technology, these tables are considered to be parts of the stream, and there is no concept for extracting these tables from the stream and recording the tables; there is no technology regarding the recording of these tables.
In addition, as mentioned earlier, in the MHP/OCAP/OCAP-DVR specifications, when acquiring the table which represents the application control information included in the broadcast wave, filter resources which extract each table are necessary. However, there is no improvement on the wasteful consumption of filter resources during reproduction of a broadcast wave stored in a recording area.
In addition, particularly during “trick play” (high-speed reproduction, skip reproduction), it is difficult to use these filter resources to extract the table in real-time from the broadcast wave stored in a recording area. In particular, regarding acquisition during skip reproduction of a table which has position information of a skip destination (NPT coefficient), it is necessary to acquire a table in which that position information is multiplexed with a previous/next time which differs from the time of reproduction of the video/audio; however, depending on general filter resources, it is not possible to acquire such a table in which the time of reproduction of the video/audio is multiplexed with the different previous/next time. Because of this, it is preferable to accumulate each table extracted during accumulation in a form different from the broadcast wave, thus reducing the table extraction processing during reproduction. However, Patent Reference 1 does not improve upon the following problem: when reproducing a broadcast wave that is stored in a recording area, a format is taken in which the broadcast wave re-formed from the stored data is reproduced, and during reproduction through this format, processing of extracting each table from the broadcast wave is necessary; therefore, table extraction during “trick play” is difficult.